<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .demo{
            background-color: orange;
        }
    </style>
</head>
<body>

    <button id="btn">点我创建一个输入框</button>
    <script type="text/javascript">
        const btn = document.getElementById('btn');
        btn.onclick = ()=>{
            const input = document.createElement('input');

            input.className = 'demo';
            input.value=99;
            input.onclick = ()=>{alert(1)}

            document.body.appendChild(input);

            input.focus();
            input.parentElement.style.backgroundColor='skyblue'
            console.log(input.parentElement)
        }
    </script>
</body>
</html>